1. Field of the Invention
The present invention relates to a connector for optical fiber used for an optical communication part, such as an optical data link.
2. Description of the Prior Art
FIG. 1 is a schematic structural view of a connector for optical fiber, in which reference numeral 10 designates a plug and 13 designates a module provided with a receptacle 14, the module 13 comprising the receptacle 14, internal optical elements 15 and 16 therein, and an electronic circuit being connected with these components. Optical fiber cords 1 are connected either separately or in a bundle to other apparatus and connected at the ends to the plug 10. In other words, the utmost end of each optical fiber cord 1 is bared of its cover and fitted into each metallic ferrule 4 serving to protect the bared portion of the cord 1. The ferrules 4 each project at a moderate length from a housing 11 at the plug 10 which restrains and holds therein the base ends of optical fiber cords 1 or ferrules 4.
The projecting ferrules 4 are inserted through projections 11a attached to the housing 11 and somewhat project from the projections 11a respectively.
The projections 11a are inserted into a housing 17 at the receptacle 14 and optical fibers inserted into the ferrules 4 abut against optical elements 15 and 16 within the module 13 fitted to the receptacle 14.
The module 13 contains therein the opto-electrical transfer element 15 and electro-optical transfer element 16 which are juxtaposed with each other and held to the module 13, the elements 15 and 16 being connected to the receiving side circuit and the transitting side circuit (which are not shown) respectively.
FIG. 2 is a partially cutaway plan view of the conventional plug 10. A rubber boot 12 is fitted onto the end of each optical fiber cord 1, the ends of cords 1 being fitted into the housing 11 at the connector plug 10.
The optical fiber cord 1 comprises optical fiber 1a having a cladding of polymer series and a core of quartz, the optical fiber 1a being sleeved with a nylon jacket 1b and further with a sheath 1e of P.V.C. or the like. Also, the optical fiber cord 1 within the housing 11 is bared from the end of sheath 1e of a jacket 1b of nylon.
The optical fiber 1a is bared at a portion from the utmost end of the bared jacket 1b, so that the ferrule 4 is fitted onto the utmost end of the sheath 1e, the jacket 1b bared from the utmost end thereof, and the optical fiber 1a bared from the utmost end of the jacket 1b. The ferrule 4 forms a flange 61 at the base and is reduced in diameter in a stepping manner at the outer periphery of an intermediate portion.
A through bore 62 is formed at the axis of the ferrule 4 and reduced in diameter at an intermediate portion in a stepped manner to thereby be tapered toward the utmost end. The utmost end of the sheath 1e of the optical fiber cord 1 is fitted into the root of the through bore 62, both the ferrule 4 and cord 1 being fixed with silicon resin or epoxy resin 64. The jacket 1b bared of the sheath 1e from the utmost end and the optical fiber 1a bared of the jacket 1b from the utmost end are inserted into the through bore 62, the end face of the optical fiber 1a being level with the end face of ferrule 4 and facing the exterior. The utmost end of the through bore 62 at the ferrule 4 and the utmost end of the optical fiber 1a are fixed to each other with silicon resin or epoxy resin 65.
Onto the root of the ferrule 4, a tubular member 71 is fixedly fitted and a washer 74 of a leaf spring is slidably fitted, the tubular member 71 forming a flange at one end at the optical fiber 1a end side and abutting at the other end against a flange 61 at the ferrule 4. Meanwhile, a holder 72 is fixedly fitted into the groove at an intermediate portion of the ferrule 4 and being mounted in the housing 11 and a cushion 73 is interposed to be compressed longitudinally between the holder 72 and the washer 74 so that the entire ferrule 4 is biased by the cushion 73 in the direction of projecting (in the right direction of FIG. 2) from the housing 11.
The aforesaid connector for optical fiber fixes the sheath 1e for the optical fiber cord 1, jacket 1b and ferrule 4, and the optical fiber 1a and ferrule 4, by using an adhesive, such as silicon resin or epoxy resin, whereby not only it takes much time to cure the adhesive but also the long-term reliability thereof is poor. Also, the processing for the connector is that the adhesive is leaked from between the optical fiber 1a and the ferrule 4 and attached onto the utmost end face of the optical fiber 1a to be cured, and thereafter the leaked adhesive is polished and removed, thereby creating a problem in that the polishing process takes much time and the terminal treatment is troublesome. In addition, the conventional terminal treatment takes 30 to 40 minutes.